Lifting jack



M. B. LUCKER LIFTING JACK Nov. 14, 1939.

Filed Sept. 30, 1935 2 Sheets-Sheet 1 INVENTOR.

fldlarclizacltez? ATTORNEYS.

Nov; 14, 1939. M. B. LUCKER 2,179,577

LIFTING JACK Filed Sept. 50, 1935 2 Sheets-Sheet 2 INVENIOR.

ATTORNEY-.5.

J17 lizard/BI u cker Patented Nov. 14, 1939 UNITED STATES PATENT oFFice LIFTTING JACK Application September 30, 1935, Serial No. 42,755

12 Claims.

This invention relates to lifting jacks, and more particularly to a bumper jack of the ratchet operating type which is particularly adapted for use in raising automotive vehicles and like devices.

It is an object of the invention to produce a new and improved operating mechanism for a lifting jack; and more particularly to provide an operating mechanism of the pawl and ratchet type which is simple to construct and assemble and which is durable, reliable and eflicient in operation.

More specifically the invention contemplates the provision of an operating mechanism having a pair of operating pawls engageable with a screw shaft, the pawls being flexibly connected whereby each controls the operation of the other and wherein control means is provided for varying the action of the pawl connections to provide for the raising and lowering of the load lifting member.

Further objects and advantages of the invention will be apparent from the following description when taken in connection with the accompanying drawings wherein there is illustrated one preferred embodiment of the invention.

In the drawings, wherein like reference numerals refer to like parts throughout:

Figure 1 is a side elevation of a lifting jack embodying the principles of the invention.

Figure 2 is a top View of the jack.

Figure 3 is a partial section taken along the line 33 of Figure 1.

Figure 4 is a perspective detail of the spring which operatively connects the operating pawls.

Figure 5 is a detail perspective of the control lever.

Figure 6 is a detail perspective of the holding pawl.

Figure 7 is a detail perspective of the actuating pawl.

Figure 8 is a detail perspective of the cushion collar carried by the actuating pawl.

Figures 9 to 12 inclusive are partial sectional views showing the successive steps of operation of the operating mechanism as the load lifting casting is lowered; and

Figures 13 to 16 inclusive are similar views showing the successive steps of operation as the load lifting casting is raised.

The embodiment shown in the drawings for purposes of illustration comprises a base Ill to which there is secured, by any suitable means, an upstanding screw shaft or standard II. The shaft H has a helical thread l2 extending along the major portion of its length. As shown, the bottom edge I3 of the thread is tapered downwardly to facilitate the movement of the operating pawls along the thread. A lifting casting I5 is mounted upon the screw shaft for movement therealong under the control of the jack operating mechanism. The lifting casting has its load contacting portions l6 formed in the upper end thereof. As best shown in Figure 2, there may be three such portions extending around the casting, any one of which may be engaged with the load. In Figure 1 the load is shown as the bumper I! of an automotive vehicle, as the jack construction of the present invention is especially adapted for use as a bumper jack. However, it is to be understood that the jack may be engaged with other portions of the vehicle or used to raise various types of loads. The lifting casting is freely rotatable about the screw shaft or standard II to facilitate the engagement of any one of the load engaging portions IS with the load.

It is to be noted that the load contacting projections l6 have V-shaped bumper engaging notches. These notches guide the bumper bar into position and effectively hold it from accidental disengagement. The provision of a plurality of projections in connection with the rotatability of the lifting casting permits the application of the jack to the bumper in a plurality of ways which insures ready application regardless of the space and operating conditions under which the jack must be applied. It is further to be noted that the upper end of the lifting casting l5 may be raised appreciably beyond the upper end of the standard shaft l I during the lifting operation. The lifting casting thus, by reason of its length and construction, increases the lifting height of the jack, allowing the use of a shorter standard shaft which facilitates storage of the jack within an automobile tool compartment.

The holding pawl I9 is pivoted to an extending lower portion of the lifting casting by means of a pivot pin 20. The pawl is freely mounted upon the pivot for operative movement into engagement with the thread l2 of the screw shaft. Also loosely mounted upon the pivot pin 20 is an operating handle 2| adapted to be reciprocated about the pivot pin by means of any suitable operating bar receivable within an opening 22 formed in the end thereof. An actuating pawl 24 is loosely pivoted to the operating handle by means of a pivot pin 25 for operative engagement with the thread of the screw shaft. The actuating pawl carries a projection 26 upon which is mounted a cushion collar 21. This cushion collar may be formed of rubber or any other suitable resilient material. A fiexure spring 29 formed into the general configuration shown in Figure 4 has its larger loop portion embracing the collar and its smaller loop portion loosely encircling a stud 30 projecting from the holding pawl l9. The spring, together with the cushion collar, forms a resilient connecting means between the two pawls so that each controls the operation of the other. Pivoted to the lifting casting at 32 is a control lever 33. The inner end of the control lever is adapted for engagement against the spring whereby to control the lifting or lowering of the casting l5 as the operating handle is actuated. In Figure 1 the control lever is shown released in the position.

it occupies when the casting I5 is being lowered. The control lever is movable to the position shown in Figure 13 in engagement with the spring to effect the lifting of the casting.

The operation may be best understood by reference to Figures 9 to 16 inclusive. Referring first to Figures 9 to 12 which show the condition of the operating parts as the lifting casting is lowered, it will be seen that under this condition of operation the control lever 33 is in its released position which allows the fiexure spring 29 free and unimpeded movement. The normal or starting position is shown in Figure 9 with the pawls in engagement with the threads of the screw shaft as shown. As the operating handle 2! is raised to the position of Figure 10, the actuating pawl 24 is drawn upwardly therewith around the pivot 20. This movement brings the cushion collar carried by the actuating pawl into engagement with the flexure spring at the point 35 which produces an outward force upon the actuating pawl away from the threads of the screw shaft so that when the pawl has been lifted. sufficiently to clear the top edge of the thread 36, it will snap away and be carried outwardly from the thread to the position shown in Figure 10. Accordingly, as the operating handle is now lowered to the position of Figure 11, the end of the actuating pawl, on being carried downwardly therewith, will first engage and ride down the outer flat side of the thread 36 and then move underneath the thread into engagement with the thread 3?. Continued downward movement of the operating handle after the end of the actuating pawl has become seated upon thread 31 causes a slight lifting of the casting it? about the pivot 25 sufficient to permit the end of the holding pawl to clear the thread 38. The holding pawl snaps outwardly to the position shown in Figure 11 by reason of the outward pressure of the rubber cushion against the spring at the point 39. This outward pressure upon the spring causes the spring to snap the holding pawl into the position shown so that upon subsequent raising of the operating handle, the holding pawl which is lowered with the casting is around pivot 25 slips alongside and underneath the thread 38 and becomes seated upon the thread 40. The parts, as shown in Figure 12, have now returned to their starting position as in Figure 9, with the exception that the pawls have been stepped downwardly one tooth upon the screw shaft and the casting I5 has been correspondingly lowered. Repeated operation continues the downward movement of the casting as much as may be desired to lower the load.

To cause lifting of the casting R5, the control lever 33 is first moved to the position shown in Figures 13 to 16. The normal position of the parts preparatory to the lifting operation is as shown in Figure 13' wherein the spring loosely embraces the cushion collar substantially as in Figure 9. However, if an attempt should now be made to raise the operating handle, as during the lowering of the jack, the actuating pawl 24 would not be released from the tooth 35 as in Figure 10 due to the fact that the operative engagement between the control lever and the spring would prevent such action. To raise the jack; the operating handle is lowered instead of raised from the position of Figure 13 to that shown in Figure 14. This causes the lifting of the casting !5 due to the raising of the pivot pin 26 about the axis 25, and the holding pawl 19 is correspondingly raised from the thread 38 to a position above the thread ll. During this upward movement of the holding pawl, it is kept in constant pressure engagement with the screw threads due to the contact between the control lever and the spring at the point M, such contact causing an inward pressure upon the spring which transmits the inward pressure to the holding pawl. As the operating handle is now lifted to the position shown in Figure 15, the holding pawl is first lowered into engagement with the thread 4! and thereafter the actuating pawl will be lifted by the handle as it pivots around the now stationary pivot 29. During this movement the actuating pawl is kept in constant pressure engagement with the threads due to the inward pressure between the control lever and the spring at the point 33 and between the spring and the cushion collar at the point at. Inward force is transmitted to the actuating pawl by means of the spring and the cushion collar. As the operating handle is now slightly lowered, as shown in Figure 16, the actuating pawl is brought into engagement with the thread 41% and the parts have assumed their normal position as shown in Figure 13 except that the pawls have been raised one thread and the casting l5 has been correspondingly lifted, Repeated operation of the operating handle causes continued raising of the casting i5 and the load as much as may be desired. The control lever 33 will remain in the position shown in contact with the spring until manually released,

It will be noted that the pawls allow free upward movement of the casting H5 at all times so that the casting may be rapidly lifted into engagement with the load along the screw shaft without manipulation of the operating handle 2 I. Likewise the pawls permit rotation of casting l5 about the screw shaft whereby to facilitate the application of contacting portions E6 to the load.

The construction is simple and may be readily assembled. At the same time it is durable, reliable and efficient in operation. It is obvious that various modifications may be shown in the precise embodiment of the invention used for the purpose of illustration. The invention is accordingly not to be limited to the precise construction shown, but only as indicated in the following claims. No claim is made herein to the general jack structure apart from the ratchet and pawl operating mechanism, such claims being presented in other copending cases.

The invention is hereby claimed as follows:

1. A lifting jack comprising a base, a load lifting member, and means to raise the lifting member relative to the base comprising a ratchet, a pair of pawls cooperating therewith, and resilient means connecting the pawls whereby each controls the action of the other, said resilient means comprising a fiexure spring and a compression member of resilient material and adapted to engage the flexure spring.

2. A lifting jack comprising a base, an upstanding ratchet shaft mounted thereon, a load lifting member adapted for movement along the shaft, and means for moving the member comprising a pair of pawls mounted on the member and engageable with the shaft, resilient means connecting the pawls whereby each controls the operation of the other, and lever means to actuate the pawls for causing lifting of the member with respect to the ratchet, said lever being operable to lift the member when actuated downwardly.

3. A lifting jack comprising a base, an upstanding ratchet shaft mounted thereon, a load lifting member adapted for sliding movement along the shaft, and means for sliding the member comprising a pair of pawls carried by the member and engageable with the shaft, resilient means connecting the pawls whereby each con trols the operation of the other, means engageable with the resilient means to modify the control of the pawls, and lever means to actuate the pawls for causing lifting of the member with respect to the ratchet, said lever being operable to lift the member when actuated downwardly.

4. A lifting jack comprising a base, a load lifting member and means to raise the load lifting member relative to the base, comprising a ratchet on the base, a pair of pawls carried by the load lifting member and cooperating therewith, resilient cam means interconnecting the pawls whereby each pawl controls the action of the other, lever control means connected to the pawls to raise the lifting member when the lever is moved downwardly, and means engageable with the resilient means to modify the control of the pawls.

5. In a lifting jack, a base, a load lifting member and means to raise the load lifting member relative to the base, comprising a ratchet on the base, a holding pawl and an actuating pawl carried by the load lifting member, a resilient member connected to one of the pawls, said resilient member having a cam portion engageable with a follower on the other pawl, said cam and follower being operative to bring the pawls relatively into engagement with the ratchet during movement of the lifting member in one direction, and being operable to release at least one of the pawl members from the ratchet during movement of the lifting member in the opposite direction, and lever control means connected to the pawls to raise the lifting member when the lever is moved downwardly.

6. In a lifting jack, a base, a load lifting member and means to raise the load lifting member relative to the base, comprising a ratchet on the base, a holding pawl and an actuating pawl carried by the load lifting member, a resilient cam member connected to one of said pawls, a cam follower member connected with the other of said pawls and being engageable with said cam, a lever control means connected to the pawls to relatively move the pawls to raise the lifting member when the lever is moved downwardly, said cam and cam follower members being so arranged as to create a camming action under the influence of the aforesaid relative movement of the pawls to shift the pawls relatively to the ratchet member to engage or disengage the pawls from said ratchet member for controlling the raising of the lifting member in accordance with the operation of the lever.

7. A vehicle jack comprising a supporting column, a member slidably mounted on said column, mechanism to actuate said member along said column, said mechanism'comprising an actuating lever pivoted to said member, a holding detent pivoted to said member, a lifting pawl pivoted to said lever, and a spring connecting said pawl and detent having a pivoted connection with said detent and a lost motion connection with said pawl, and reversing means for said mechanism.

8. A vehicle jack comprising a supporting column, a member slidably mounted on said column, ratchet mechanism to actuate said member along said column, said mechanism comprising an actuating lever pivoted to said member, a holding detent pivoted to said member, a lifting pawl pivoted to saidilever, a spring connecting said pawl and detent, a reversing lever pivoted to said member for actuation against and away from said spring, said spring being elongated having one end pivoted to said holding detent and having the other end reversely bent to provide a restricted loop, and means on said lifting pawl disposed in said restricted loop.

9. A vehicle jack comprising a supporting rack bar, a member slidably mounted on said rack bar, operating mechanism to actuate said member along said rack bar, said mechanism comprising an actuating lever pivoted to said memher, a holding detent pivoted to said member, a lifting pawl pivoted to said lever, and a spring having a substantially enclosed loop at one end and connecting said detent and pawl, said spring having a pivoted connection with said detent and a lost motion connection with said loop to said pawl, and reversing means for said mechanism.

10. A vehicle jack comprising a toothed column, a member mounted on said column for slidable movement relative thereto, and mechanism to actuate said member along said column, said mechanism comprising an actuating lever pivoted to said member, a holding detent pivoted to said member, a lifting pawl pivoted to said lever, and means connecting said holding detent and said lifting pawl for effecting operative movement of said holding detent by the movement of said lifting pawl under predetermined conditions of operation, the point of connection of said means to said holding detent being normally offset from the straight line between the pivoted point of said holding detent and the point of connection of said means with said lifting pawl, the connection between said connecting means and lifting pawl having lost motion.

11. A vehicle jack comprising a toothed column, a member mounted on said column for slidable movement relative thereto, and mechanism to actuate said member along said column, said mechanism comprising an actuating lever pivoted to said member, a holding detent pivoted to said member, a lifting pawl pivoted to said lever, and means connected to said lifting pawl by a lost motion connection to withdraw said holding detent from engagement with said column as the result of a predetermined movement of said lifting pawl.

12. A lifting jack comprising a base, an upstanding ratchet shaft mounted thereon, a load lifting member having a load engaging portion at its upper end, said member embracing said shaft and being adapted for sliding movement therealong, and means for sliding the member along the shaft comprising a holding pawl pivoted to the member and adapted for engagement pawl controls the movement of the other, and a shift control lever pivoted to the member and engageable with the spring to vary the control whereby to selectively effect upward or downward sliding of the lifting member along the 5 shaft as the operating handle is actuated.

MILLARD B. LUCKER. 

